make sure matcher respects argument order for non-commutative ops (#847)

src/ngraph/pattern/matcher.cpp

@@ -26,18 +26,6 @@ namespace ngraph
 {
     namespace pattern
     {
-        static std::vector<std::shared_ptr<Node>> get_arguments(std::shared_ptr<Node> n)
-        {
-            std::unordered_set<std::shared_ptr<Node>> arguments;
-            for (const auto& input : n->get_inputs())
-            {
-                arguments.insert(input.get_output().get_node());
-            }
-
-            return std::vector<std::shared_ptr<Node>>(
-                begin(arguments), end(arguments)); //vector is needed for generating permutations
-        }
-
         std::shared_ptr<Node> Matcher::match_root() { return m_match_root; }
         bool Matcher::match_pattern(const std::shared_ptr<op::Label>& label,
                                     const std::shared_ptr<Node>& graph_node,
@@ -62,7 +50,7 @@ namespace ngraph
 
             if (is_match) //in case label was already bound this rebinds it to the same node (harmless; and the logic seems cleaner)
             {
-                auto args = get_arguments(label);
+                auto args = label->get_input_ops();
                 if (args.size() > 0)
                 {
                     if (args.size() != 1)
@@ -95,7 +83,7 @@ namespace ngraph
             }
             else
             {
-                auto args = get_arguments(any);
+                auto args = any->get_input_ops();
                 if (args.size() != 1)
                 {
                     throw ngraph_error("Any can only take one argument");
@@ -165,8 +153,8 @@ namespace ngraph
                          << "pattern = " << pattern_node->get_name() << " "
                          << "matched " << graph_node->get_name();
 
-            auto args = get_arguments(graph_node);
-            auto pattern_args = get_arguments(pattern_node);
+            auto args = graph_node->get_input_ops();
+            auto pattern_args = pattern_node->get_input_ops();
 
             if (args.size() != pattern_args.size())
             {

test/pattern.cpp

@@ -458,6 +458,16 @@ TEST(pattern, matcher)
     ASSERT_TRUE(n.match(make_shared<op::Abs>(label), make_shared<op::Abs>(add)));
     ASSERT_EQ(n.get_pattern_map()[label], add);
 
+    //Correct argument order
+    ASSERT_FALSE(n.match(b - a, a - b));
+    auto aab = a * (a - b);
+    auto paab = pattern * (pattern - b);
+    ASSERT_TRUE(n.match(paab, aab));
+    auto aba = a * (b - a);
+    ASSERT_FALSE(n.match(paab, aba));
+    auto paba = pattern * (b - pattern);
+    ASSERT_FALSE(n.match(paba, aab));
+
     //Correlations
     auto label1 = std::make_shared<pattern::op::Label>(a);
     auto tmp = label1 + b;